commit 7fa8f3a4f3ccc8b1828fd03d4f26cfda0ed0bf51
author Mike Klein <mtklein@google.com> Tue Dec 03 11:00:57 2019 -0600
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Tue Dec 03 17:55:20 2019 +0000
tree 9d1f370c0811af8303a8db248c3433021d9dca64
parent a7bb87ed532df9db52bc12341e9f33b6ad563fdb

Fix sprite blitter choice logic

While we're asking if there are any color space xform steps to do,
let's look at all 5 of them, including whether we need to unpremul or
premul.  The sprite blitter paths this logic guards can't handle
any change in color space _or_ alpha type, so this is a perfect fit.

Without this fix, we'd happily draw premul into unpremul using memcpy().
(Unpremul -> premul was already guarded by the check with my new note.)

Change-Id: Ic8d9e69f6c7bd2902ff77393de1da9cd940ea826
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/257657
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

src/core/SkBlitter_Sprite.cpp

diff --git a/src/core/SkBlitter_Sprite.cpp b/src/core/SkBlitter_Sprite.cpp
index 89b107b..6ae7893 100644
--- a/src/core/SkBlitter_Sprite.cpp
+++ b/src/core/SkBlitter_Sprite.cpp
@@ -57,7 +57,7 @@
 public:
     static bool Supports(const SkPixmap& dst, const SkPixmap& src, const SkPaint& paint) {
         // the caller has already inspected the colorspace on src and dst
-        SkASSERT(!SkColorSpaceXformSteps::Required(src.colorSpace(), dst.colorSpace()));
+        SkASSERT(0 == SkColorSpaceXformSteps(src,dst).flags.mask());
 
         if (dst.colorType() != src.colorType()) {
             return false;
@@ -178,13 +178,14 @@
     */
     SkASSERT(allocator != nullptr);
 
+    // TODO: in principle SkRasterPipelineSpriteBlitter could be made to handle this.
     if (source.alphaType() == kUnpremul_SkAlphaType) {
         return nullptr;
     }
 
     SkSpriteBlitter* blitter = nullptr;
 
-    if (!SkColorSpaceXformSteps::Required(source.colorSpace(), dst.colorSpace())) {
+    if (0 == SkColorSpaceXformSteps(source,dst).flags.mask()) {
         if (!blitter && SkSpriteBlitter_Memcpy::Supports(dst, source, paint)) {
             blitter = allocator->make<SkSpriteBlitter_Memcpy>(source);
         }